Nonwoven fabric webs may be useful in a wide variety of applications. Various nonwoven fabric webs may comprise spunbond, meltblown, spunbond (“SMS”) webs comprising outer layers of spunbond thermoplastics (e.g., polyolefins) and an interior layer of meltblown thermoplastics. Such SMS nonwoven fabric webs may comprise spunbond layers which are durable and an internal meltblown layer which is porous but which may inhibit fast strikethrough of fluids, such as bodily fluids, for example, or the penetration of bacteria through the fabric webs. In order for such a nonwoven fabric web to perform to particular characteristics, it may be desirable for the meltblown layer to have a fiber size and a porosity that assures breathability of the nonwoven fabric web while at the same time inhibiting the strikethrough of fluids.
Absorbent articles such as diapers, training pants, incontinent wear and feminine hygiene products, for example, may also utilize nonwoven fabric webs for many purposes such as liners, transfer layers, absorbent media, barrier layers and cuffs, backings, and other components. For many such applications, the barrier properties of the nonwoven fabric web play an important role in the performance of the fabric webs, such as the performance as a barrier to fluid penetration, for example. Absorbent articles may comprise multiple elements such as a liquid permeable topsheet intended to be placed next to the wearer's skin, a liquid impermeable backsheet which forms, in use, the outer surface of the absorbent article, various barrier cuffs, and an absorbent core disposed between the topsheet and the backsheet.
When absorbent articles are produced, webs of materials, such as nonwoven materials, are bonded to each other. The bonding of these materials can be done for example via a mechanical bonding process. Reducing the manufacturing cost of absorbent articles by reducing the basis weight of the webs while preserving, if not improving, their functionality remains a challenge. For example, it is believed that when the combined basis weight of the webs to be bonded is less than 30 gsm, a reduction in basis weight of currently available spunbond, or SMS nonwoven webs can result in a significantly higher rate of bond defects. Those defects can lead to increased leakage of the absorbent article. There remains a need to provide an absorbent article comprising low basis weight webs that have a high quality of bonds with a low rate of defect when webs are bonded together.
There is also a need for low basis weight nonwoven webs that may be used in the manufacture of absorbent articles at high production rates and packaged under significant compaction for extended periods of time while achieving and maintaining soft, air permeable (i.e. breathable) and liquid barrier materials with good tactile properties and good barrier properties to low surface tension fluid. Structural, mechanical and fluid-handling properties of available nonwoven webs are believed not to be sufficient. Therefore, there is also a need for improved nonwoven web structures.
An additional way to improve the liquid imperviousness of a nonwoven to liquids such as urine, menses, and loose fecal matter is to treat the nonwoven with a composition that renders the nonwoven, or portions thereof, more hydrophobic, for example, by coating the nonwoven with a composition containing one or more silicone polymers. Examples of surface coatings for improving the barrier properties of a nonwoven are disclosed in U.S. Publication Nos. 2005/0177123 and 2006/0189956. Known silicone containing coatings are typically formed as hydrophilic solutions (e.g., an emulsion of a polar liquid component such as water, a non-polar liquid component such as silicone oil, and other optional ingredient(s) such as surfactant(s) and stabilizer(s)).
Accordingly, it would be also desirable to provide an absorbent article that includes a material with improved barrier properties such as a hydrophobic surface coating.